Hi Paul
There is no method 'out-of-the-box' that you could take advantage of, but wav is a very simple container format and it would be pretty easy to write your own. This diagram is a popular one that shows the format - to down-sample you simply need to modify the sample rate value, data chunk size and the data samples themselves to get what you want.
Alternatively you can explore what OpenAL might be able to provide. If it can do that for you (I am not very nowledgable in OpenAL so am not sure) then writing cascades hooks into it should be straight-forward.
BVP
